A communications network typically comprises a plurality of network elements which conduct communications over the network. Using a local area network (LAN) of a business office as an example, a personal computer (PC) sitting on someone's desk is a network element. It communicates with other network elements to exchange data, such as communicating with another desktop PC via interoffice e-mail or retrieving a word processing document from a data server on the network.
The network also includes element managers 4a-4c, the function of which is to control communications between the network elements on the network and are generally invisible to the user of a network element. Each element manager is responsible for controlling a subset of the network elements. In large networks, there may be an even higher control node, termed a network manager, which is in communication with the element managers and generally acts as a manager for the element managers.
The present application is primarily concerned with these larger type networks in which a plurality of element managers each control a plurality of network elements. In such networks, it is frequently desirable to have some type of back-up system to allow network elements to continue to operate even if the element manager which is responsible for controlling the element cannot do so, for instance, due to the manager becoming disabled or due to a fault in the communication path between the manager and the agent.
In one known redundancy back-up scheme, all of the hardware of the manager and/or the data required by the manager for proper operation of the network is duplicated. Thus, if the primary hardware becomes disabled, the secondary hardware simply takes over and keeps the element manager in operation. Such schemes are typically extremely limited in how far apart the two sets of hardware can be from each other due at least to cabling requirements.
One problem with this prior art back-up scheme is that the back-up hardware system is essentially in the same location as the primary system. Accordingly, they cannot offer protection in situations where the cause of the disablement of the primary system is an external force which effects the entire locale. Examples of such events include fire, natural disaster, insurrection and other wartime calamities. Such events are of particular concern in developing nations.
Another known scheme involves having duplicate hardware at a remote location and replicating part of the application data over a high speed link. If the hardware at the primary location fails, the secondary hardware at the remote location can take over using the replicated data. Such schemes suffer from the need of a costly high speed data link between the primary hardware and the remote backup hardware. Also, this type of backup scheme is only possible with limited types of networks.
Accordingly, it is an object of the present invention to provide an improved communications network.
It is another object of the present invention to provide an improved back-up scheme for a communications network.
It is yet another object of the present invention to provide a back-up scheme for a communications network wherein the back-up hardware is at a geographically distant location from the primary hardware.
It is a further object of the present invention to provide a remote geographic redundancy scheme for shifting control of network elements from a disabled network manager to one or more other element manager sites.